The inflammatory response, the body’s defence reaction to injury, commonly involves swelling, raised temperature of the surrounding tissues, redness, pain, loss of function. The RICE protocol of Rest, Ice, Compression and Elevation aims to reduce swelling, temperature and pain although there is debate about the wisdom of curtailing this essential physiological response: see http://stoneathleticmedicine.com/2013/11/why-ice-and-anti-inflammatory-medication-is-not-the-answer/. Icing for 5 to 10 mins per hour is, however routinely recommended by many medics, physios and sports massage therapists. After my ACL operation, the swelling in and around the joint was the main cause of discomfort and certainly a factor in loss of function.
A cryocuff (a device connected to a reservoir of ice cold water which circulates to cool the joint) being prohibitively expensive, I bought a pump-up knee cuff incorporating a removable gel pack which you put in the freezer (and then back on your knee, for best results, nincom). It is useful because you can move about with it on instead of lashing slippery gel packs to your leg which slither off in all directions, risking further comedic banana-skin-type injury. Reputedly at least 90% of venous return in the lower leg is effected by the deep veins being squeezed by muscular contraction. I was pretty conservative with the pumping up part but ended up with sudden bruising in my lower leg. Either the lymphatic system was impeded or the blood in the swollen knee was forced down into the lower leg. Either way, caution with the compression element of this useful piece of kit might be advisable. Best to use the compression bit with the foot elevated instead of ranging around your house pretending you are a fit person on holiday.